Alternatively, there may be an internal clock that regulates the timing of spore wall formation that is independent of meiotic division.

With bird watching being a popular recreation for many folks in Wirth Park, concern has been expressed over the potential adverse effects of artificial lights for night skiing on the internal clocks of our feathered friends.

The team also found that while ultraviolet light is required for sun-compass navigation, some other wavelength of light was required for setting the butterflies' internal clocks.